Update Axes.grid keyword to use 'visible'

[eagoetz]

This PR updates the Axes.grid keyword arguments to use visible that is needed because of upstream matplotlib updates.

This PR replaces #368

[codecov]

Codecov Report

Merging #383 (f5d3cde) into master (b5559a4) will not change coverage.
The diff coverage is 9.09%.

@@           Coverage Diff           @@
##           master     #383   +/-   ##
=======================================
  Coverage   50.17%   50.17%           
=======================================
  Files          60       60           
  Lines        8685     8685           
=======================================
  Hits         4357     4357           
  Misses       4328     4328           

Flag	Coverage Δ
Linux	50.17% <9.09%> (ø)
python3.10	50.17% <9.09%> (ø)
python3.11	50.17% <9.09%> (ø)
python3.9	50.17% <9.09%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
gwsumm/plot/core.py	84.18% <0.00%> (ø)
gwsumm/plot/triggers/core.py	17.82% <0.00%> (ø)
gwsumm/plot/noisebudget.py	20.49% <0.00%> (ø)
gwsumm/plot/segments.py	21.89% <0.00%> (ø)
gwsumm/plot/builtin.py	21.72% <20.00%> (ø)

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[eagoetz]

@iaraota I have double-checked that using visible=True or visible=False works fine using matplotlib>=3.5